// Copyright 2011 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_UNICODE_H_
#define V8_UNICODE_H_

#include <sys/types.h>
#include "src/globals.h"
#include "src/third_party/utf8-decoder/utf8-decoder.h"
#include "src/utils.h"
/**
 * \file
 * Definitions and convenience functions for working with unicode.
 */

namespace unibrow {

typedef unsigned int uchar;
typedef unsigned char byte;

/**
 * The max length of the result of converting the case of a single
 * character.
 */
const int kMaxMappingSize = 4;

#ifndef V8_INTL_SUPPORT
template <class T, int size = 256>
class Predicate {
public:
    inline Predicate() = default;
    inline bool get(uchar c);

private:
    friend class Test;
    bool CalculateValue(uchar c);
    class CacheEntry {
    public:
        inline CacheEntry()
            : bit_field_(CodePointField::encode(0) | ValueField::encode(0))
        {
        }
        inline CacheEntry(uchar code_point, bool value)
            : bit_field_(
                CodePointField::encode(CodePointField::kMask & code_point) | ValueField::encode(value))
        {
            DCHECK_IMPLIES((CodePointField::kMask & code_point) != code_point,
                code_point == static_cast<uchar>(-1));
        }

        uchar code_point() const { return CodePointField::decode(bit_field_); }
        bool value() const { return ValueField::decode(bit_field_); }

    private:
        class CodePointField : public v8::internal::BitField<uchar, 0, 21> {
        };
        class ValueField : public v8::internal::BitField<bool, 21, 1> {
        };

        uint32_t bit_field_;
    };
    static const int kSize = size;
    static const int kMask = kSize - 1;
    CacheEntry entries_[kSize];
};

// A cache used in case conversion.  It caches the value for characters
// that either have no mapping or map to a single character independent
// of context.  Characters that map to more than one character or that
// map differently depending on context are always looked up.
template <class T, int size = 256>
class Mapping {
public:
    inline Mapping() = default;
    inline int get(uchar c, uchar n, uchar* result);

private:
    friend class Test;
    int CalculateValue(uchar c, uchar n, uchar* result);
    struct CacheEntry {
        inline CacheEntry()
            : code_point_(kNoChar)
            , offset_(0)
        {
        }
        inline CacheEntry(uchar code_point, signed offset)
            : code_point_(code_point)
            , offset_(offset)
        {
        }
        uchar code_point_;
        signed offset_;
        static const int kNoChar = (1 << 21) - 1;
    };
    static const int kSize = size;
    static const int kMask = kSize - 1;
    CacheEntry entries_[kSize];
};

class UnicodeData {
private:
    friend class Test;
    static int GetByteCount();
    static const uchar kMaxCodePoint;
};

#endif // !V8_INTL_SUPPORT

class Utf16 {
public:
    static const int kNoPreviousCharacter = -1;
    static inline bool IsSurrogatePair(int lead, int trail)
    {
        return IsLeadSurrogate(lead) && IsTrailSurrogate(trail);
    }
    static inline bool IsLeadSurrogate(int code)
    {
        return (code & 0xfc00) == 0xd800;
    }
    static inline bool IsTrailSurrogate(int code)
    {
        return (code & 0xfc00) == 0xdc00;
    }

    static inline int CombineSurrogatePair(uchar lead, uchar trail)
    {
        return 0x10000 + ((lead & 0x3ff) << 10) + (trail & 0x3ff);
    }
    static const uchar kMaxNonSurrogateCharCode = 0xffff;
    // Encoding a single UTF-16 code unit will produce 1, 2 or 3 bytes
    // of UTF-8 data.  The special case where the unit is a surrogate
    // trail produces 1 byte net, because the encoding of the pair is
    // 4 bytes and the 3 bytes that were used to encode the lead surrogate
    // can be reclaimed.
    static const int kMaxExtraUtf8BytesForOneUtf16CodeUnit = 3;
    // One UTF-16 surrogate is endoded (illegally) as 3 UTF-8 bytes.
    // The illegality stems from the surrogate not being part of a pair.
    static const int kUtf8BytesToCodeASurrogate = 3;
    static inline uint16_t LeadSurrogate(uint32_t char_code)
    {
        return 0xd800 + (((char_code - 0x10000) >> 10) & 0x3ff);
    }
    static inline uint16_t TrailSurrogate(uint32_t char_code)
    {
        return 0xdc00 + (char_code & 0x3ff);
    }
};

class V8_EXPORT_PRIVATE Utf8 {
public:
    using State = Utf8DfaDecoder::State;

    static inline uchar Length(uchar chr, int previous);
    static inline unsigned EncodeOneByte(char* out, uint8_t c);
    static inline unsigned Encode(char* out,
        uchar c,
        int previous,
        bool replace_invalid = false);
    static uchar CalculateValue(const byte* str, size_t length, size_t* cursor);

    // The unicode replacement character, used to signal invalid unicode
    // sequences (e.g. an orphan surrogate) when converting to a UTF-8 encoding.
    static const uchar kBadChar = 0xFFFD;
    static const uchar kBufferEmpty = 0x0;
    static const uchar kIncomplete = 0xFFFFFFFC; // any non-valid code point.
    static const unsigned kMaxEncodedSize = 4;
    static const unsigned kMaxOneByteChar = 0x7f;
    static const unsigned kMaxTwoByteChar = 0x7ff;
    static const unsigned kMaxThreeByteChar = 0xffff;
    static const unsigned kMaxFourByteChar = 0x1fffff;

    // A single surrogate is coded as a 3 byte UTF-8 sequence, but two together
    // that match are coded as a 4 byte UTF-8 sequence.
    static const unsigned kBytesSavedByCombiningSurrogates = 2;
    static const unsigned kSizeOfUnmatchedSurrogate = 3;
    // The maximum size a single UTF-16 code unit may take up when encoded as
    // UTF-8.
    static const unsigned kMax16BitCodeUnitSize = 3;
    static inline uchar ValueOf(const byte* str, size_t length, size_t* cursor);

    typedef uint32_t Utf8IncrementalBuffer;
    static inline uchar ValueOfIncremental(const byte** cursor, State* state,
        Utf8IncrementalBuffer* buffer);
    static uchar ValueOfIncrementalFinish(State* state);

    // Excludes non-characters from the set of valid code points.
    static inline bool IsValidCharacter(uchar c);

    // Validate if the input has a valid utf-8 encoding. Unlike JS source code
    // this validation function will accept any unicode code point, including
    // kBadChar and BOMs.
    //
    // This method checks for:
    // - valid utf-8 endcoding (e.g. no over-long encodings),
    // - absence of surrogates,
    // - valid code point range.
    static bool ValidateEncoding(const byte* str, size_t length);
};

struct Uppercase {
    static bool Is(uchar c);
};
struct Letter {
    static bool Is(uchar c);
};
#ifndef V8_INTL_SUPPORT
struct V8_EXPORT_PRIVATE ID_Start {
    static bool Is(uchar c);
};
struct V8_EXPORT_PRIVATE ID_Continue {
    static bool Is(uchar c);
};
struct V8_EXPORT_PRIVATE WhiteSpace {
    static bool Is(uchar c);
};
#endif // !V8_INTL_SUPPORT

// LineTerminator:       'JS_Line_Terminator' in point.properties
// ES#sec-line-terminators lists exactly 4 code points:
// LF (U+000A), CR (U+000D), LS(U+2028), PS(U+2029)
V8_INLINE bool IsLineTerminator(uchar c)
{
    return c == 0x000A || c == 0x000D || c == 0x2028 || c == 0x2029;
}

V8_INLINE bool IsStringLiteralLineTerminator(uchar c)
{
    return c == 0x000A || c == 0x000D;
}

#ifndef V8_INTL_SUPPORT
struct ToLowercase {
    static const int kMaxWidth = 3;
    static const bool kIsToLower = true;
    static int Convert(uchar c,
        uchar n,
        uchar* result,
        bool* allow_caching_ptr);
};
struct ToUppercase {
    static const int kMaxWidth = 3;
    static const bool kIsToLower = false;
    static int Convert(uchar c,
        uchar n,
        uchar* result,
        bool* allow_caching_ptr);
};
struct V8_EXPORT_PRIVATE Ecma262Canonicalize {
    static const int kMaxWidth = 1;
    static int Convert(uchar c,
        uchar n,
        uchar* result,
        bool* allow_caching_ptr);
};
struct V8_EXPORT_PRIVATE Ecma262UnCanonicalize {
    static const int kMaxWidth = 4;
    static int Convert(uchar c,
        uchar n,
        uchar* result,
        bool* allow_caching_ptr);
};
struct V8_EXPORT_PRIVATE CanonicalizationRange {
    static const int kMaxWidth = 1;
    static int Convert(uchar c,
        uchar n,
        uchar* result,
        bool* allow_caching_ptr);
};
#endif // !V8_INTL_SUPPORT

} // namespace unibrow

#endif // V8_UNICODE_H_
